iray multi gpu rendering

[nonnulla]

Hello,

installed a 1070 and a 2060 super
iray worked with both for 2 weeks then stopped
i tried everything on software drivers side without success also formatted
found some people with same issue, found also a lot of people with really different setups working without problems with multi gpu systems with same gpus, mixed rtx and mixed rtx gtx also with old 7xx and 1xxx series

after some months yesterday i upgraded my pc case fans
removed both gpus, at restart got a gpu error, cant remember what exactly sry, something about wrong drivers
rebooted again without problems
then ive seen the light and re-enabled the 2nd gpu in iray and bang, its working again!

After this im confused, its drivers error? after months of drivers updates, reinstalls, clean reinstalls, voodoo practices etc?
i thought it was something about an hw damage cause of the heat, but why is now working again?

now, im planning to buy a new rtx 3xxx (yeah i know, i hope i will be lucky enough)
but...if i get the same issue?

any suggestion about a possible origin of the issue?

my specs

ryzen 7 3700x
asus x570 pro
1070
2060 super